The device forming the subject of the invention is for recording, storing and restoring, without contact or electrical connection and without out an electric supply, variable information which another device has communicated thereto without contact or electrical connection.
The function performed by this device is called "dynamic coding".
At the present time, dynamic coding is achieved in two ways:
(a) With magnetic-doublet based devices which, depending on their magnetic polarity, modify the frequency of an oscillator into .+-..DELTA.f, the interpretation of the direction of .DELTA.f being associated with a bit 1 or 0. The disadvantages of magnetic-doublet systems are that the information is transmitted in parallel form and therefore the size of the system is a function of the extent of this information, that the coding syptem is expensive and complicated and that the material forming the magnetic doublets is very special and the supply of which is delicate.
(b) With a battery of frequency emitters which act on a battery of frequency receivers: the information received actuates bistable relays which bring into operation or not frequency emitters different from the preceding ones and which restore their frequency to a battery of receivers themselves distinct from the preceding ones. The disadvantages of this system appear in the fact that the information is transmitted in parallel form and that the size of the system is linked to the extent of this information (this size is increased by the fact that the emitters interfere with each other and that they must then be spaced apart), in the fact that memorization is achieved by means of bistable relays which may offer contact hazards in cases of vibration and in the fact that it requires the use of a large number of means, much wiring and so impaired reliability.